Deep rifts remain to be healed inside the ruling party following December's power struggle, which resulted in Mr Zuma and his allies taking most of the top jobs, BBC southern Africa correspondent Peter Biles says.

'Best ever'

Mr Mbeki was speaking in his annual state of the nation address, which our correspondent says was eagerly anticipated.

I am aware of the fact that many in our society are troubled by a deep sense of unease about where our country will be tomorrow

President Thabo Mbeki

"I have absolutely no doubt that we will honour our undertaking to Fifa and the world community of soccer players and lovers to create all the necessary conditions for the holding of the best ever Fifa Soccer World Cup tournament," he said.

He apologised for the scale of the problems caused by the power cuts and said they would be resolved "in a relatively short period".

"It is... necessary to take this opportunity to convey to the country the apologies of both the government and [state power utility] Eskom for the national emergency."

Mr Mbeki has faced calls from business leaders to act over the black-outs, which at one stage stopped production at some of the country's biggest gold and platinum mines.

He has overseen steady economic growth but critics say the benefits have not reached most people.

"I am aware of the fact that many in our society are troubled by a deep sense of unease about where our country will be tomorrow," he said.

Opposition Democratic Alliance leader Helen Zille said President Mbeki had not managed to calm the nerves of the South African nation.

The man who succeeded Nelson Mandela as president of South Africa is to step down next year after a decade in office.

After becoming ANC leader, Mr Zuma is favourite to become South Africa's next president in 2009, unless he is found guilty in his corruption trial which is due to begin in August.